This invention pertains generally to spreading tools for applying viscous materials, particularly to devices for applying viscous materials to a surface efficiently while producing a uniform layer of material, and more particularly to a device for smoothly applying viscous materials along two planar surfaces having a common edge simultaneously with substantially no excess material applied to any surface.
During the building or repair of physical structures, various viscous materials are used to fill and/or seal cracks and gaps in and between structural elements. Examples of viscous materials are caulk, cement, joint compound, spackle, and grout. Numerous tools have been developed to apply the various viscous materials to any number of building materials, such as wood, concrete, sheet rock, drywall, asphalt, cinder, etc. One such style of tool is a caulking-gun which applies a thin bead of material to intersections between one wall and other surface. Caulking-guns are generally used in sealing bathtub, shower, and tile seams. However, the thin bead is not generally spread or smoothed once it is applied, and because of the thin bead, a wide swath is not possible.
Alternatively, spreading tools consisting of one or more blade edges are laid flat against a surface and pulled downward spreading the viscous material. Traditionally, three separate tools are needed—one for applying material to an inside corner, one for applying material to an outside corner, and a third for applying material along a flat surface. Conventional corner tools do not uniformly distribute pressure exerted by the user. The inside corner tool must be laid flat against the corner, pushed in, and pulled down. As a result of this non-uniform pressure distribution, the drywall tape gets caught on the bottom of the tool. This snagging begins pulling and dragging the tape off the wall. Often the user must go back and readjust the tape and start all over again. Moreover, this tool can only be used for inside corners. It has no other purpose. Except for the very skilled artisan this tool makes the job very time consuming and difficult. The outside corner tool is very similar to the inside corner tool but is designed specifically for outside corners. Due to the placement of the handle and the angle at which the tool is configured, it can only be used for outside corners. It too has no other purpose. Additionally, both of the current inside and outside corner tools are incapable of adding the viscous material to the surfaces prior to spreading. A flat surface tool is used to place an amount of the material onto the surface being worked upon and the corner tool is then used to spread and smooth that material. Therefore, when working on corner applications, at least two tools are needed—a flat surface tool and a corner tool. To simply matters, the flat surface tool is the tool most professionals use for corners obviating the need for a corner tool. The problem using this approach is that the sharp edge on the flat surface tool gouges the drywall tape in the corners. It is also difficult to keep a straight edge in inside corners with this tool. Additionally, the flat surface tool is configured to finish only one side of a corner at a time which slows down the finishing process because one must wait for one side of the corner to dry before applying compound to the other side. This additional time increases labor cost and decreases efficiency
Examples of spreading tools are disclosed in the following patents: U.S. Pat. No. 5,067,889 issued to Humiston discloses a hand tool for smoothing joint compound in wide angle applications. The blade is designed to be flexible and to fit within angles formed by adjoining wall boards between 90 and 180 degrees. The blade has a crease in the center of one outer edge and a handle attached in the center of the opposite outer edge. Importantly, the crease is directly in line with the longitudinal midline of the handle. The handle position prevents a user from applying proper force during flat area applications.
In U.S. Pat. No. 5,192,558 to Sparrow an adjustable hand tool/trowel is discussed. The trowel has a first flat blade similar to that of a standard putty knife, but the blade has two spring-loaded attachments down its length extending from the handle. The handle of the trowel has a trigger mechanism which, when in operation, causes the blade to bend under the spring pressure. Various angles can be formed depending on the amount of pressure applied to the trigger. Importantly, this design is for flat surfaces and those above 180 degrees.
U.S. Pat. No. 5,467,497 issued to Greene discloses an adjustable hand tool/trowel having a hinge along the blade extending from the handle. The hinge is adjustable to fit internal angles made by adjoining walls. A locking pin bolt mechanism can be used to control the angle made by the blades. Importantly, the handle of the '497 patent is located along the pivot point and extended upwardly into the angle made by the folding blades. This layout prevents the trowel from being used on outside corners. Additionally, the locking pin mechanism disrupts the flat edge of the blade preventing its use in flat application scenarios.
In U.S. Pat. No. 5,774,924 issued to Beckham, et al a hand held tool/trowel having a thinned inner portion for flexible bending is disclosed. Each end of the blade has a pivoting mount. The mount is pivotally connected to a handle using a set of arms. The trowel is designed for use on outside angles formed by two pieces of drywall. The flexible hinge allows the blade to be used for applications between 180 and 270 degrees. The handle prevents it use for internal corner applications.
U.S. Pat. No. 5,792,489 issued to Liberman discloses a hand held tool/trowel for applying joint compound to interior corners formed by two layers of drywall. The trowel has a blade bent at 90 degrees and a handle attached to the acute portion of the bend. The external ends of the blade are bent outwardly from the handle. This additional bend forces the interior portion of the blade to lie flush against the opposing walls during application of compound. Importantly, this tool is designed for interior 90 degree corners. The handle, along with the additional bend, does not allow for use in flat surface applications. Further, the handle prevents the use of the tool for outside edge applications.
Finally, U.S. Pat. No. 6,880,198 to Hazard describes a hand held tool for application of viscous materials such as cement, caulk, and joint compound. The tool possesses a handle and blade wherein the blade has a forward working edge. Alongside the blade is an extension edge. The tool is designed to be used for acute angles. The compound is applied with the working edge while the extension edge prevents excess material from working around the working edge. When used on drywall, this tool is designed only to be used along one wall of the inside angle.
Therefore, it is clear that a need exists for a single multi-purpose tool that quickly and easily applies viscous material to joints and corners so that the edges are smoothly covered with material along a distance of several inches from the corner. Furthermore, it is readily apparent that there is a long felt need for an all-in-one viscous material spreading tool capable of smoothly applying material to inside corners, outside corners, and flat surfaces.